Pacemaker

Cross-Section of the Chest With a Pacemaker

This illustration shows a cross-section of the chest with a pacemaker. Figure A shows the location and general size of a double chamber, or double lead, pacemaker in the upper chest. The wires with electrodes are inserted into the right atrium and ventricle of the heart through a vein in the upper chest. Figure B shows the electrode electrically stimulating the heart muscle. Figure C shows the location and general size of a single chamber, or single lead, pacemaker in the upper chest. The wire with the electrode is inserted into the right ventricle of the heart through a vein in the upper chest.

What is a Pacemaker?

When there’s a problem with your heart’s electrical system, a pacemaker can help. A pacemaker is a small, lightweight, electronic device that’s placed inside your body. The pacemaker keeps track your heartbeat and when necessary, generates electrical signals similar to the heart’s natural signals. These signals keep your heart beating at an appropriate rate.

A pacemaker helps keep your heart from beating too slowly, but it doesn’t stop your heart from beating on its own. The pacemaker “listens” to your heart. When the hearts own electrical system sends a signal and the heart beats, the pacemaker waits and does nothing. When the hearts system misses a signal, the pacemaker sends a signal to replace it.

Your cardiologist/electrophysiologist will choose the type of pacemaker that’s best for you. A pacemaker with one lead is called a single-chamber pacemaker. A pacemaker with two leads is called a dual-chamber pacemaker. Single chamber and dual-chamber pacemakers are typically used for cardiac rhythm disorders involving a too slow heart rate (bradycardia) which can be caused because of slow electrical impulses (sick sinus syndrome) or because the electrical impulses get delayed on their way through the heart (heart block).

When you’re active, your heart beats at a faster pace or rate. Electrical system problems can sometimes keep your heart’s rate from speeding up when needed. Because of this, single-chamber and dual-chamber pacemakers can be programmed to be rate-adaptive. This means that they can help change the rate of your heartbeat depending upon your activity level. So with activity a rate-adaptive pacemaker helps your heart beat faster, and when you sit down to rest, the pacemaker lets your heart return to a slower rate.

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